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    <p>For a full set of comparison functions I have used the following mixin, which you could put in say for example a mixin.py in your module.</p> <pre><code>class ComparableMixin(object): def _compare(self, other, method): try: return method(self._cmpkey(), other._cmpkey()) except (AttributeError, TypeError): # _cmpkey not implemented, or return different type, # so I can't compare with "other". return NotImplemented def __lt__(self, other): return self._compare(other, lambda s, o: s &lt; o) def __le__(self, other): return self._compare(other, lambda s, o: s &lt;= o) def __eq__(self, other): return self._compare(other, lambda s, o: s == o) def __ge__(self, other): return self._compare(other, lambda s, o: s &gt;= o) def __gt__(self, other): return self._compare(other, lambda s, o: s &gt; o) def __ne__(self, other): return self._compare(other, lambda s, o: s != o) </code></pre> <p>To use the mixin above you need to implement a _cmpkey() method that returns a key of objects that can be compared, similar to the key() function used when sorting. The implementation could look like this:</p> <pre><code>&gt;&gt;&gt; from .mixin import ComparableMixin &gt;&gt;&gt; class Orderable(ComparableMixin): ... ... def __init__(self, firstname, lastname): ... self.first = firstname ... self.last = lastname ... ... def _cmpkey(self): ... return (self.last, self.first) ... ... def __repr__(self): ... return "%s %s" % (self.first, self.last) ... &gt;&gt;&gt; sorted([Orderable('Donald', 'Duck'), ... Orderable('Paul', 'Anka')]) [Paul Anka, Donald Duck] </code></pre> <p>The reason I use this instead of the total_ordering recipe is <a href="http://bugs.python.org/issue10042" rel="nofollow">this bug</a>. It's fixed in Python 3.4, but often you need to support older Python versions as well.</p>
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    1. COIt's worth pointing out to anyone finding this answer that the `mixin` module is a hypothetical module one could define — it's not in the Python standard library.
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    2. COYeah, clarified this.
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